Any synthetic ATF will be great. I would drain the reservoir and refill. Wait a week, put a drop of the fluid on a white paper napkin and see if there is any dirt settling out in it. if there is repeat weekly until that stops.
Topped up with almost 1L of fluid so i assume id already lose most of it anyway! A couple of full locks on the wheel eradicated the noise and i had to loosen the belt believe it or not. When i tried to tighten it the car stuttered on acceleration.
I assume the monster 1L engine didn't have enough power to turn the taught belt as from what i can tell tightening the aux belt also tightens the power steering belt.